“…For the latter, different approaches are applied to structure the microprobes. These include boron-doping used as wet etch-stop (Wise et al, 1970;Najafi et al, 1985;Takahashi and Matsuo, 1984;Leong et al, 1990), combined dry and wet etching of silicon (Kewley et al, 1997;Yoon et al, 2000), or only dry etching procedures (Errachid et al, 2001;Wassum et al, 2008;Herwik et al, 2009) including also the use of SOI substrates (Ensell et al, 2000;Norlin et al, 2002;Cheung et al, 2003). Each probe is patterned with multiple thin-film electrodes along the length of the shaft adapted to specific experimental requirements and allows parallel recordings from several sites on a single, implanted microprobe.…”